Additive manufacturing and repair typically involves:
1. Spreading a layer of metal filler powder over a working surface;
2. Traversing an energy beam over the powder to melt it, creating a new working surface; and
3. Repeating from step 1 until the component is built or restored.
This process is often conducted under a blanket of an inert gas such as argon to protect the melt pool from oxidation and to protect the powder from hydration. Flux may be added to the metal powder to cleanse the melt of contaminants, thereby forming slag that solidifies on top of the deposited material, thereby continuing to provide protection from oxidation if the blanket of inert gas dissipates before the deposited material is sufficiently cooled. However, slag can interfere with the energy beam, and the solidified slag must be removed between layering steps, so additive manufacturing and repair is inconvenienced and slowed by slag formation.
Superalloy materials are difficult to fabricate and repair due to their high melting points and susceptibility to weld solidification cracking and strain age cracking. They can have melting point ranges of 1200 to 1400° C. and higher, and are used for components in the hot gas path in gas turbine engines. A superalloy is a highly corrosion and oxidation resistant alloy with excellent mechanical strength and resistance to creep at high temperatures. A superalloy usually includes combinations of Ni, Co, Cr, and sometimes Fe, plus lesser amounts of W, Mo, Ta, Nb, Ti, and Al. Nickel-based superalloys contain more nickel than any other constituent—usually at least 40 wt. % Ni—and may contain little or no Fe or Co. Examples of superalloys include alloys sold under the trademarks and brand names Hastelloy, Inconel alloys (e.g. IN 738, IN 792, IN 939), Rene alloys (e.g. Rene N5, Rene 41, Rene 80, Rene 108, Rene 142, Rene 220), Haynes alloys (282), Mar M, CM 247, CM 247 LC, C263, 718, X-750, ECY 768, 282, X45, PWA 1480, PWA 1483, PWA 1484, CMSX single crystal alloys (e.g., CMSX-4, CMSX-8, CMSX-10), GTD 111, GTD 222, MGA 1400, MGA 2400, PSM 116, IN 713C, Mar-M-200, IN 100, IN 700, Udimet 600, Udimet 500 and titanium aluminide.